DE3622584A1 - METHOD AND DEVICE FOR REGULATING THE DISTANCE OF A RIBBON IN A TEXTILE MACHINE - Google Patents

Description

The invention relates to a method and an apparatus for Regulation of the warping of a sliver at a textile factory machine in which a sliver first measures mass fluctuations send the first measuring element, then one after the first measuring element neat drafting system with an adjustable draft and finally a subordinate to the drafting system and the mass passes through second measuring element measuring length unit, whereby the draft of the drafting system to compensate for fluctuations in mass of the sliver depending on the measured and time hesitates evaluated mass fluctuations and the difference in measured mass per unit length and a predefinable target value for the mass per unit length is changed.

Such a method is known from DE-PS 29 12 576. There, the absolute cross-section of a fiber sliver is measured at the outlet of a textile machine and compared with a predetermined fixed target value. Furthermore, the relative cross-sectional fluctuations of the sliver are measured at a point in the direction of the belt run before the outlet. The mean value of these fluctuations is formed over a limited period of time and compared with the current cross-sectional fluctuations. From the measurement signals obtained, a mixed signal is formed in a manner not described in more detail which controls a regulating device for regulating the cross section of the fiber sliver.

The object of the invention is a method and a Vorrich creating a regulation for the warping of a sliver, in which the delivery of a sliver is as constant as possible tape weight per unit length is guaranteed.

The problem is solved in that in a method of type mentioned at the outset from the difference in the measured mass and the predefinable setpoint with the aid of a first control a target variable is obtained, from the difference with the ge measured and delayed evaluated mass fluctuation with With the help of a second control, a manipulated variable for setting the draft of the drafting system is generated.

Since it is the measured mass with regard to the stretch work is a feedback variable, forms the first re setting a control loop, which measures the measured mass on the front regulable setpoint. In contrast is the second regulation Part of a control circuit, since the measured Mas s fluctuation with regard to the drafting system pelte greatness. One size of the control circuit is from Control loop obtained setpoint. The control circuit is therefore from Control loop overlaid. This has the consequence that on the one hand the Mass fluctuations of the sliver optimally from the control circuit can be compared and that on the other hand due to the overlaid is always guaranteed that the Sliver has the desired mass per unit length.

In an embodiment of the method according to the invention, a ge shared scheme used, with between the profit the setpoint and the generation of the manipulated variable tet and the target variable and the manipulated variable temporarily stored will. With the help of switching and buffering it is possible to control the control circuit and the superimposed control circuit to carry out with a regulation.  

In a development of the method according to the invention Switching depending on the belt speed of the sliver controlled. This causes, for example, at an increased tape speed, the switching between control circuit are increased in the same way, so that overall the accuracy of the regulation process is the same remains.

In a device for performing the invention Procedures are means of obtaining the target size and Er Generation of the manipulated variable in the form of an electronic digita len control unit, in particular a programmable Mikrocom puters provided. In this way it is possible to use Ver using less known components a high accuracy of To achieve regulatory proceedings.

In one embodiment of the device, a clock is generated signals means for measuring the tape running speed of the Provided sliver, especially a digital, with the Drafting device coupled speed sensor. By using the Speed encoder, for example an increment encoder, is in simple control of the switching depending reached by the sliver speed of the sliver.

In a further development of the device, the measured mass fluctuations provided a shift register. Especially in connection with a digital control unit provides a way to use a shift register represents the necessary time delay of the measured Generate fluctuations in mass in a simple manner. The number the register positions of the shift register depend on the arrangement of the drafting system and the measuring elements, as well as in Depends on the desired accuracy of the regu determination process.

Further features and advantages of the invention result from the following description of two embodiments of the same ben, which are shown in the drawing. It shows

Fig. 1 is a schematic block diagram of a first embodiment of the invention, which in particular in the form of an analog circuit and can be used to continuously regulate the distortion of the fiber band and

Fig. 2 is a schematic block diagram of a second embodiment of the invention, which is constructed in particular in the form of a digital circuit and can be used to regulate the distortion of the fiber band in discrete, clock-dependent times.

In Figs. 1 and 2, the regulating path of a textile machine is schematically illustrated. This serves to warp and compensate for fluctuations in mass of a fiber sliver passing through it.

The autoleveller of FIGS. 1 and 2 essentially consists of a first measuring element (12), three draw roller pairs (14, 15, 16) and a second measuring element (18). The pairs of stretching rollers ( 14, 15, 16 ) form a drafting arrangement ( 25 ) in a known manner, the draft of which can be adjusted. A sliver ( 10 ) passes through the first measuring element ( 12 ), the pairs of stretching rollers ( 14, 15, 16 ) and the second measuring element ( 18 ) in succession.

The pairs of stretching rollers ( 14, 15 ) are driven together by an electric motor ( 20 ) at a variable speed, while the pair of stretching rollers ( 16 ) is driven by an electric motor ( 21 ) at a fixed speed. This results in a delay of the serbands ( 10 ) between the pairs of stretching rollers ( 14, 15, 16 ), which is dependent on the difference in the rotational numbers of the electric motors ( 20, 21 ) and the ratio of the circumferences of the pairs of stretching rollers ( 14, 15, 16 ).

To set the speed of the electric motor ( 20 ) it is connected to an actuator ( 23 ) which in turn is struck by at least one input signal, namely a manipulated variable (SG) .

The arranged in the tape running direction of the sliver ( 10 ) before the stretching roller pairs ( 14, 15, 16 ) first measuring element ( 12 ) measures the fluctuations in mass of the sliver ( 10 ) and forms an output signal (MS) . The pair of stretching rollers ( 14, 15, 16 ) nachgeord Nete second measuring element ( 18 ) measures the mass per unit length of the fiber band ( 10 ) and forms an output signal (ML) . The two measuring elements ( 12, 18 ) are known, for example capacitive transducers, which will not be explained in more detail here.

In the regulating section shown schematically in FIGS . 1 and 2, the drafting of the drafting device ( 25 ) is set such that, on the one hand, fluctuations in mass of the sliver ( 10 ) are compensated for and, on the other hand, the sliver ( 10 ) has a desired, predefinable mass per unit length. For this purpose, as will be explained below, the manipulated variable (SG) , with the aid of which the draft of the drafting system ( 25 ) can be set, is dependent on the measured fluctuations in mass (MS) and the measured mass per unit length (ML) of the fiber band ( 10 ) formed.

In Fig. 1, a setpoint generator ( 35 ), in particular a potentiometer or the like is provided, with the help of which a user can specify the desired mass per unit length for the sliver ( 10 ). From this, the setpoint generator ( 35 ) forms a setpoint (SW) which is linked ( 45 ) to the measured mass per unit length (ML) in the form of a difference and fed to a first control ( 40 ). Depending on the setpoint (SW) and the measured mass per unit length (ML) , the control unit ( 40 ) obtains a setpoint (SX) according to predetermined control algorithms.

The mass fluctuations ( MS) of the serband ( 10 ) measured by the measuring element ( 12 ) are delayed with the aid of a delay device ( 30 ), in particular a delay line or the like, and result in time-delayed mass fluctuations (MSZ) at the output of the delay device ( 30 ) . The time delay caused by the delay device ( 30 ) is selected such that the mass fluctuation measured at a specific point in the serb belt ( 10 ) comes into effect precisely when the manipulated variable (SG) is formed when this point of the sliver ( 10 ) arrives the delay point ( 26 ) of the drafting system ( 25 ) has arrived. The delay time by which the fluctuations in mass (MS) are delayed corresponds to the running time of the fiber sliver ( 10 ) from the measuring element ( 12 ) to the tension point ( 26 ) of the drafting device ( 25 ), which is roughly between the last two pairs of drafting rollers ( 15, 16 ).

The time-delayed mass fluctuations (MSZ) are linked ( 47 ) to the target variable (SG) in the form of a difference and fed to a second control ( 42 ). According to predetermined control algorithms, this generates the above-mentioned manipulated variable (SG) as a function of the time-delayed fluctuations in mass (MSZ) and the target variable (SX ) , with the aid of which the draft of the drafting unit ( 25 ) can be adjusted.

Since the second measuring element is arranged downstream of the drafting device ( 25 ), the first control ( 40 ) belongs to a control loop. In contrast, the second control ( 42 ) is part of a control circuit, since the first measuring element ( 12 ) is arranged upstream of the drafting system ( 25 ) and the fluctuations in mass (MS) therefore form a variable that is also coupled. The setpoint (SX) formed by the control loop influences the control loop so that the control loop is overlaid overall.

For example, if the target value (SW) for the desired mass per unit length of the fiber sliver ( 10 ) is equal to the measured mass per unit length (ML) , then the target variable (SX) formed by the control loop is zero. The result of this is that the control circuit influences the drafting device ( 25 ) in such a way that the measured and time-delayed mass fluctuations (MSZ) become zero. If, on the other hand, the setpoint (SW) is greater than the measured mass per unit length (ML) of the fiber band ( 10 ), the control loop forms a positive setpoint (SX), for example. The consequence of this is that the control circuit influences the delay of the drafting device ( 25 ) in such a way that the measured and time-delayed evaluated mass fluctuation (MSZ) is not completely compensated, but a positive mass fluctuation is sought. This compensates for the deviation of the measured mass per unit length from the desired setpoint. Overall, the setpoint (SX) is always formed by the control loop in such a way that the control circuit influences the delay of the drafting device ( 25 ) not only with regard to compensating for mass fluctuations in the fiber sliver ( 10 ), but also with regard to keeping the Mass per unit length of the sliver ( 10 ).

The schematically shown in FIG. 1 and described above be described regulation method can be carried out, for example, with the aid of an analog electronic circuit. It is expedient to carry out the entire process continuously, that is to say to continuously influence the drafting device ( 25 ). However, it is also possible to carry out the method in a time-discrete manner, that is to say to influence the drafting device ( 25 ) only at certain, successive times. An example of such a time-discrete embodiment is shown schematically in FIG. 2.

In Fig. 2, the output signals (MS, ML) of the two measuring elements ( 12, 18 ) are fed to a digital electronic microcomputer ( 99 ) which provides the manipulated variable (SG) as the output signal. The manipulated variable (SG) is in the same way on the mass fluctuations (MS) and the measured mass per length unit (ML) of the fiber band ( 10 ), as has already been explained in connection with FIG. 1, so that with regard on their function, the embodiments of FIGS. 1 and 2, in particular with respect to the control and of the control loop, respectively.

In contrast to the embodiment of FIG. 1, however, only one regulation ( 60 ) is provided in the embodiment of FIG. 2, which is used jointly by the control and regulating circuits. Switchovers are provided for this purpose, which are shown in FIG. 2 in the form of switching devices ( 70 to 74 ). Furthermore, intermediate storage ( 80, 81, 82 ) are provided in the embodiment of FIG. 2, with the aid of which the setpoint (SX) generated by the control loop is temporarily stored. Finally, the microcomputer ( 99 ) contains an analog / digital converter ( 85 ) which is used to convert the analog signals (MS, ML) into digital signals.

It is understood that the switching devices ( 70 to 74 ), the buffers ( 80, 81, 82 ), the control ( 60 ) and. The like does not have to be present in the microcomputer ( 99 ), but its function can also be implemented within a program sequence or the like. The same applies in particular to the variables occurring within the microcomputer ( 99 ), for example the target variable (SX) . These quantities can occur both as electrical quantities, but also, for example, as binary quantities within a program run.

In the switching positions of the switching devices ( 70 to 74 ) shown in FIG. 2, the control loop is activated. The common switching of the switching devices ( 70 to 74 ) into their switching position, not shown, has the result that the control circuit is switched over to the control circuit. The switches of the switching devices ( 70 to 74 ) are controlled as a function of a clock signal (T) , which is generated with the aid of a rotary encoder ( 95 ), in particular a digital increment encoder, which is coupled to one of the pairs of stretching rollers ( 14 ) and its clock corresponds to the sliver speed of the sliver ( 10 ). It is also possible to generate the clock signal (T) purely as a function of time, that is to say to perform the switchovers after constant time intervals.

If, as shown in FIG. 2, the control circuit is activated, the measured mass per unit length (ML ) is fed to the buffer store ( 80 ) and buffered by it. After the conversion by means of the analog / digital converter ( 85 ), the measured mass per unit length (ML) is linked ( 65 ) with the target value (SW) for the desired mass per unit length of the fiber band ( 10 ), forming the difference and together used control ( 60 ) supplied. The setpoint (SW) is generated by a digital setpoint generator ( 36 ), in particular, on which the desired mass per unit length of the fiber band ( 10 ) can be set by a user. The output signal formed by the control ( 60 ) as a function of the setpoint (SW) and the mass per unit length (ML) is fed to the buffer ( 81 ), so that the setpoint last obtained from the control circuit is obtained at the output of the buffer ( 81 ) at any moment (SX) is available.

If the control circuit is activated, the switching devices ( 70 to 74 ) are in their opposite switching positions, not shown, so the mass fluctuations (MS) from the buffer ( 80 ) are temporarily stored, converted by the analog / digital converter ( 85 ) and then fed to a shift register ( 31 ), the number of Re register places, as will be explained, in particular depending on the distance of the measuring element ( 12 ) and the delay ( 26 ) of the drafting device ( 25 ). The shift register ( 31 ) is controlled by the clock signal (T) in such a way that the stored values are "shifted" from register to register in a known manner depending on the clock. With the help of the shift register ( 31 ), the measured mass fluctuations (MS) are delayed in time, so that the measured time-delayed mass fluctuations (MSZ) are available at the output of the shift register ( 31 ).

The time-delayed mass variations (MSZ) are linked at acti fourth control circuit by difference formation with the target quantity (SX) (65) and the control (60) supplied. This forms an output signal which is fed to the buffer memory ( 82 ) and stored by it. As a result, the last manipulated variable (SG) formed by the control circuit is available at any time at the output of the buffer store ( 82 ).

As in the embodiment of FIG. 1, in the embodiment of FIG. 2, the desired variable ( SX) obtained from the control loop is fed to the control loop for generating the manipulated variable (SG) . The control loop is thus superimposed on the control circuit in the same way. In contrast to the embodiment in FIG. 1, however, the setpoint variable (SX) and the manipulated variable (SG) are not continuously formed in the embodiment of FIG. 2, but alternately. This is achieved with the help of the switchovers and intermediate storage.

If the switching devices ( 70 to 74 ) are switched by the clock signal (T), for example, every two milliseconds, the sliver speed of the sliver ( 10 ) is 480 m per minute and the sliver ( 10 ) is to be drawn 8 times, this has the effect of Consequence that the distortion of the drafting device ( 25 ) is influenced by the actuator ( 23 ) every 2 millimeters of fiber sliver ( 10 ) (measuring length).

As in the embodiment in FIG. 1, in the embodiment in FIG. 2 the time delay caused by the shift register ( 31 ) must correspond to the running time of the fiber band ( 10 ) from the measuring element ( 12 ) to the drafting point ( 26 ) of the drafting device ( 25 ). So that this is the case, the number of register positions of the shift register ( 31 ) according to the ratio of the distance of the measuring element ( 12 ) and the delay point ( 26 ) of the drafting device ( 25 ) to the mentioned measuring length of, for example, 2 mm should be selected. If this distance is 10 cm, for example, then it follows that 50 memory locations are necessary.

If, as mentioned, the clock signal (T) is generated by the speed sensor ( 95 ), the clock signal (T) and thus the changeovers change proportionally with the speed of the sliver ( 10 ). This has the consequence that the aforementioned sliver length of, for example, 2 mm (measuring length) and the number of storage spaces is constant, that is to say independent of the speed of the tape run.

It is possible to control the switchovers in such a way that primarily the control circuit is activated and thus the manipulated variable (SG) is generated, for example if the control circuit is only switched once after every hundredth activation of the control circuit. In the time that is freed up by this, the microcomputer ( 99 ) can perform other calculations. However, it is also possible to almost double the number of activations of the control circuit and thus also the accuracy of the regulating process by means of the freed up time.

Claims (10)

1. A method for regulating the warping of a sliver in a textile machine, in which a sliver first a measuring measuring fluctuations first measuring element, then a downstream of the first measuring element and provided with an adjustable delay ver drafting system and finally a downstream of the drafting system and the mass per Length unit measuring second measuring element passes, the warping of the drafting device to compensate for fluctuations in mass of the sliver depending on the measured and time-delayed evaluated fluctuations in mass and the difference of the measured mass per unit length and a predeterminable target value for the mass per unit length, characterized that a target amount (SX) is obtained from the difference between the measured mass (ML) and the predeterminable desired value (SW) by means of a first control (40), one of whose difference with the measured and delayed evaluated variation in mass (MSZ) using second scheme ( 42 ) a manipulated variable (SG) for setting the draft of the drafting system ( 25 ) is generated. 2. The method according to claim 1, characterized in that a shared control ( 60 ) is used, and that between the acquisition of the target variable (SX) and the generation of the manipulated variable (SG) switched and the target variable (SX) and the manipulated variable ( SG) can be cached. 3. The method according to claim 2, characterized in that the switches are controlled as a function of the speed of the sliver ( 10 ). 4. The method according to claim 2 or 3, characterized in that the switches are controlled such that the common control system ( 60 ) mainly generates the manipulated variable (SG) . 5. Device for regulating the warp of a sliver in a textile machine, with a mass fluctuation of the serbands measuring first measuring element, with a downstream of the first measuring element and with an adjustable delay provided by an actuator drafting device for the sliver and with a downstream of the drafting device and the mass per unit length of the sliver measuring second measuring element, the distortion of the drafting system to compensate for fluctuations in mass of the sliver depending on the measured and time-delayed evaluated mass fluctuations and the difference in measured mass per unit length and a predetermined target value for the mass per unit length is characterized in that means for obtaining a target variable (SX) from the difference between the measured mass (ML) and the predetermined target value (SW) and for generating a manipulated variable (SG) from the difference between the target variable (SX) and the measured and evaluated with a time delay Mass fluctuations (MSZ) are provided to adjust the draft of the drafting system ( 25 ). 6. The device according to claim 5, characterized in that an electronic digital control unit, in particular a programmable microcomputer ( 99 ) is provided for obtaining the target size (SX) and for generating the actuating size (SG) . 7. The device according to claim 6, characterized in that for generating a clock signal (T) means for measuring the tape running speed of the sliver ( 10 ) are provided, in particular a digital, with the drafting device ( 25 ) coupled speed sensor ( 95 ). 8. The device according to claim 6 or 7, characterized in that a shift register ( 31 ) is provided for the time delay of the measured fluctuations in mass (ML) . 9. Device according to one of claims 6 to 8, characterized in that digital storage devices ( 81, 82 ) are provided for intermediate storage of the setpoint and the manipulated variable (SX and SG) . 10. Device according to one of claims 6 to 9, characterized in that an analog / digital converter ( 85 ) is provided for converting the output signals of the measuring elements ( 12, 18 ).